Along with development of mobile communication service and technologies, current service modes of the wireless network become increasingly rich. Among the service modes, short-distance data sharing between users, small-scale social and commercial activities and local specific user-oriented specific services gradually become non-negligible growth points in a wireless platform of the next stage.
A public safety scenario and corresponding requirements in Long-Term Evolution (LTE)-based D2D communication are also proposed in the 3rd Generation Partnership Project (3GPP), and have attracted broad attentions of members of the standard group. Radio emergency and public safety communication will predictably become a hot research direction in the future.
Along with technical discussions of the standard group, applications applied to scenarios of radio emergency and public safety without network coverage are emphatically discussed in conferences, and current discussions about Radio Access Network (RAN) 1 in D2D communication have determined broadcast as a major target in stage R12. No feedback is determined as a baseline condition of broadcast according to priorities in conference discussions. Under such a condition, how to improve broadcast reliability becomes particularly important. For important broadcast messages in a public safety scenario, for example, in a severe environment scenario (such as emergencies of landslide and mine cave-in), the reception of information may be unreliable because users are distributed at different positions. Therefore, reliable reception of important messages is particularly important.
During broadcast communication, particularly D2D broadcast communication, due to the mobility and uncertainty of transmitting equipment and receiving equipment, there still exists the problem of incapability of a part of equipment terminals in reception although a lower-order transmission code rate is adopted.
Retransmission is an effective means for a wireless communication system to improve spectral efficiency, but an existing system is mainly applied in a closed loop environment, and determines whether to retransmit information or not according to an Acknowledgement/Negative Acknowledgement (ACK/NACK) which is fed back. A broadcast message is usually transmitted by adopting a lower code rate to improve performance. However, in D2D communication, both transmitting equipment and receiving equipment are mobile and do not have stable coverage, so that methods purely based on increase of the transmission power, a low code rate and the like have become inapplicable to D2D broadcast, and meanwhile, how to improve D2D broadcast reliability and system throughput in the lack of feedback mechanism has become a design bottleneck.
For the problems in a related technology, there is yet no effective solution.